6mm wtin sheath cable

[oldboot]

Its there back in post #78

cheers

[finga]

You mean....
V (voltage drop)= I (the current drawn in the circuit) x R (the resistance in the cable).....this can be found in the manufacturers document or measured from the cable.
So how do you find out resistances if you don't like wading through manufacturers documentation or standards?
What's an acceptable voltage drop?

Is COLREG's legislated upon in Australia??

[TheRealAndy]

I cant beleive you 2 are still going!

Seriously, the thread was about what size wire to use, not about what he difference between standards and regulations is. I referenced the AS becuase they have lots of handy formula's which apply equally to 12 and 240V. The standards are relevant, becuase people have done the hard work for you to make stuff safe. Sure you dont have to use it, but your a mug if you dont.

Now as for using 1mm2 cable or whatever, do the maths. You soon figure out it current carry large amounts of current over distance because it will chatch on fire. This is basic ohms law. Do the maths, Power (W) = R * I².

Eventually the wire becomes so long, that its resistance will become the major part of the circuit. Then you will get a full 12V across the length of the cable and it will be the part of the circuit that will determine the current draw. NOt much use either if you want to run a motor.

So yes, you can use 1mm2 cable, but in the situation provided it was probably not a wise thing to do. Any discussion otherwise is just nitpicking and polluting thread, only confusing the person asking the original question.

Now, I am going to report this thread and ask it to be locked. If you want to argue standards, start a new thread relevent to the topic.

[timddo]

Common andy it's only 8:30am. I have another 7.6 hours of work left.

( As a matter related to this topic. I have replace the cable with 10mm2 solar cable). Winch even sounds different and works great.

Australian Stands are a guide. ETC. If you want to be a member or use ur name as part of that group. You will need to follow those standards.

[oldboot]

You mean....
V (voltage drop)= I (the current drawn in the circuit) x R (the resistance in the cable).....this can be found in the manufacturers document or measured from the cable.
So how do you find out resistances if you don't like wading through manufacturers documentation or standards?
What's an acceptable voltage drop?

Is COLREG's legislated upon in Australia??

All reasonable questions.

yes that is the formular

if you do not any have any manufacturers specs or standards available, the best you can do is measure a sample of the cable, either by measuring a preferably long sample or setting up a voltage drop test.

What is an acceptable voltage drop?.....My point exactly.
It will vary from item to item and situation to situation...... sometimes it will be a lower or higher figure than may be called in some standard.

sometimes it is simply a matter of geting it as low as you practicaly can.

Often the best option is to simply use the heaviest practical cable.

as far as the COLREGS, they most certainly are called in legeslation..I cant quote the national legeslation, but they are certainly called in the QLD acts.
And they are also mandated by international law.


As far as a given cable ( say 1mm2) not being able to carry its rated current over any length.
Unless said cable is coiled up or otherwise has it heat confined, a cable will not burn ( in fact it will perform to specification) if it is carrying less than its rated current regardless of length.

1mm2 cable 10 amps 100meters straight in open air, will run all day and all night, it might get a little warm but it wont burn......there will be an impractical amount of voltage drop at 12 voltsDC though... actually ya wont even get 10 amps out of it............ but if you ran arround 30 meters with 12 volts supply and the other end shorted........10 amps would flow and nothing would burn......bazare but true.

This is why lots of the people running large christmas lights displays run 15 to 18 volt transformers with 12 volt lamps......running realy heavy cables is simply impractical, so they bump up the supply voltage to compensate......might not be AS3000 but it is a reasonable enginered solution.....

cheers

[TheRealAndy]

Common andy it's only 8:30am. I have another 7.6 hours of work left.

( As a matter related to this topic. I have replace the cable with 10mm2 solar cable). Winch even sounds different and works great.

Australian Stands are a guide. ETC. If you want to be a member or use ur name as part of that group. You will need to follow those standards.

Lol. Yeah I got a few hours of work left. Passes the time when I wait for the computer to crunch the numbers!

I did the same on my boat for hydraulic pump for the keel. Upgraded from 6mm2 to 10mm2, and what a difference it made

[oldboot]

sereious question chaps.

both of you have just upgraded a cable run, with the no other changes, how did the voltage drop figures work out for both the old and the new cable runs.


This is an oportunity for some real science, you both plainly have noticable improvements.

Was the improvement as good or better than you expected?

cheers

[finga]

if you do not any have any manufacturers specs or standards available, the best you can do is measure a sample of the cable, either by measuring a preferably long sample or setting up a voltage drop test.s

Can this be expanded in terms of methodology including how measuring is done?
How is a voltage drop test conducted?

I am truly wanting to learn something.

[oldboot]

If I had an "unknown cable" I would prefereably get access to a long known length .
Like a 100m roll.......and use a low ohms meter like in my megger to measure the resistance of the whole roll and then work out the resistance per meter

This is very easy for lighter cable but gets harder and much less accurate as the cable gets larger and the available length gets shorter..

there are some options.
use a high accuracy low ohms meter a mate has a funky one thet even compensates for probe resistance and reads a couple of decmal places of ohms

I have seen but not used high current resistance meters that use several amps to improve accuracy.

get access to a bigger roll of cable for more length 1000m roll

do a loop on figure8 to double the length and improve accuracy

or set up a voltage drop type resistance test

Get a power supply and a load bung several amps down the cable and measure either the voltage across & current in the wire under test, or the voltages across the source, load and wire, assuming you have a known load resistance.

The heavier the cable the more current you need to get some accuracy.

Have I done the above.....yes some of them......I have measured the resistance of rolls of "mystery cable".......I have measured the resistance of rolls of cable to prove a point......and some times it has simply been quicker to probe a cable than find some specs.

I have done a voltage drop resistance test, but only in the class room and years ago.

Where do you get a full roll of cable..sometimes it is on hand, and I have had suppliers co-operate.

I have on some ocasions had to measure cable in installations where you know neither the cable length nor the cable spec.

As far as a voltage drop test.

If you have cable on hand or an existing situation.......you could do a voltage drop test.....simply run the existing set up under load or a contrived set up and measure the voltage both ends.

Of course most of this I would not do in a 240V or regulated cabling context.


I do have a reputation as a scrounger, and lots of undocumented stuff comes my way, and I do have a reputation of being able to make things work that others simply wont touch...so often I have no option but to test things to find out about them.

cheers

[Lucky_Phill]

circles........................................... .



LP